Microporous membranes are used in various electrochemical and energy storage devices such as super capacitors and batteries to separate electrodes. Batteries or super capacitors may be constructed by layering the microporous separator between an anode and cathode, then infiltrating the device with an electrolyte. For convenience, throughout this document the term “electrochemical cell” shall refer to any type of energy storage cell unless otherwise noted.
In many cases, microporous membranes may be manufactured using PVDF or other polymers. Because of the microporous nature, the membranes may be very fragile. Holes or tears in the membrane may lead to shorts between the electrodes, rendering a battery cell or an entire electrochemical device unusable. Blockages within the membranes may decrease performance by not allowing ions in the electrolyte to pass from one electrode to another.
Some batteries are constructed as multiple layers of electrodes and separators. The batteries may be wound into a cylinder, wound about a flat plate, or constructed as flat sandwiches of multiple layers.